Injuries may occur at any level of the nervous system in the brain, the spinal cord, the peripheral nerves or the muscles. Even a focal lesion in the nervous system may interrupt neural connections and lead to loss of function such as paralysis, despite the fact that the remaining neural connections are still functional
Research in the area of neuroscience, Brain-computer Interface (BCI), and Brain-Machine Interface (BMI) is directed to the use of electrical signals detected at the nervous system to produce movements or other actions at a limb bypassing areas of nervous system damage. See E. Fetz, Volitional control of neural activity: implications for brain-computer interfaces, J. Physiol. 2007, 579; 571-579. See, also, J. Donoghue, A. Nurmikko, et al., Assistive technology and robotic control using motor cortex ensemble-based neural interface systems in humans with tetraplegia, J. Physiol. 2007, 579; 601-611. See, also, J. Wolpaw, Brain-computer interfaces as new brain output pathways, J. Physiol. 2007, 579; 613-619.
Simple movement and direct control of prosthetic arm and paralyzed muscle by cortical neurons was done in monkeys. See M. Velliste et al., Cortical control of a prosthetic arm for self-feeding, Nature 2008, 453; 1098-1101. See, also, C. Moritz, S Perlmutter and E Fetz, Direct control of paralyzed muscles by cortical neurons, Nature 2008, 456; 639-642.
Neural control of prosthetic device was also done in humans with neurological motor disability. See L Hochberg et al., Neural ensemble control of prosthetic devices by a human with tetraplegia, Nature 2006, 422; 164-171.
Unfortunately, current systems for restoring neural connections lack efficient mobility, portability, and adaptability needed for use by humans.